Throttle blade control mechanism for preventing engine dieseling



Jan.' 27, 1970 D@ M. BURMA 3,491,731

THROTTLEI BLADE CONTROL MECHANISM FOR PREVENTNG ENGINE DIESELING Filedlvxaroh 22, 196s DONALD M. BURN/A INVENTOR ATTORN EYS United States Patent O rU.s. c1. 12s- 11a s claims ABSTRACT OF THE DISCLOSURE A control mechanism responsive to manifold pressure in the intake: manifold positions the throttle blade in a partially open fast idling position when the engine is idling normally and permits the throttle blade to close completely when the engine ignition is shut oif. The control mechanism also assists in engine starting and does not interfere with normal throttle blade operation even though manifold pressures might vary Widely.

SUMMARY OF THE INVENTION Numerous tests have demonstrated that adding additional air to the intake manifold of an internal combustion engine during deceleration considerably reduces the quantity of undesirable compounds in the engine exhaust. A wide Variety of devices have been proposed to admit this additional air, but each of the devices added considerable expense to the engine. While some of the prior art devices acted directly on the throttle blade itself, each contained a complicated mechanism for closing the blade to its normal idling position during the latter phase of deceleration to achieve a normal engine idling speed of about 500-600 r.p.m.

It has now deen discovered that positioning the throttle blade where the engine would idle at about 80G-900 r.p.m. reduces exhaust emissions during deceleration to an acceptable level. Such engines coupled with manual transmissions can idle at the higher r.p.m. without seriously objectionable operating characteristics except for a condition referred to as dieseling Dieseling is the tendency of the engine to continue operating after the ignition system has been turned olf, and it is caused by the ignition of the additional air-fuel mixture admitted to the engine induction system by hot deposits in the engine cylinder or, in high compression engines, by the compression ignition characteristics of the mixture in the cylinders.

Dieseling has been prevented by connecting an electrical solenoid to the engine ignition system so the solenoid is actuated whenever the engine ignition system is turned off. The plunger of the solenoid is connected to the throttle blade so actuation of the solenoid more completely closes the throttle blade, thereby' cutting off the air-fuel mixture andpreventing continued operation. A timing device was included in the electrical circuit of the solenoid and turned off the solenoid after a short period of operation to prevent unnecessary loss of electrical energy. While this electrical system operated satisfactorily, it was far too expensive to become commercially acceptable.

The control means provided by this invention responds to intake manifold pressure to permit the throttle blade to close further whenever dieseling conditions are present, thereby reducing the amount of air-fuel mixture and halting any dieseling. In an internal combustion engine having a metering device such as a carburetor to the intake manifold, the control means of this invention comprises a movable stop adapted to position the throttle blade in an engine idling position or an engine stopping position whenever the conventional throttle closing means moves the throttle blade toward its closed position. A pressure re- 3,491,737 Patented Jan. 27, 1970 ICC sponsive device that communicates with the intake manifold is connected to the stop and is arranged so the stop is moved to the engine idling position when manifold pressure in the intake manifold is relatively low and to the engine stopping position when the manifold pressure is relatively high. The stop is not directly connected to the throttle blade, and the throttle blade is positioned in the conventional manner during normal engine operation without any `interference from the stop.

'BRIEF DESCRIPTION OF THE DRAWINGS FIGURE l is a sche-matic showing a sectional view of the control mechanism of this invention with the movable stop positioning the throttle blade in an engine stopping position. FIGURE 2 is an improved arrangement in which the control mechanism is a greatly simplied, completely sealed construction.

DETAILED DESCRIPTION Referring to FIGURE 1, the lower part of a conventional carburetor is designated by numeral 10. Carburetor 10 contains an induction passage 12, and a conventional throttle blade 1-4 is mounted in induction passage 12. A flange 16 at the lower end of carburetor 10 is fastened to a corresponding flange 18 on the intake manifold 20 of an internal combustion engine. Induction passage 12 accordingly communicates with the passage in intake manifold 20.

Throttle blade 14 is fastened to a shaft 22 that is rotatably mounted in carburetor 10. Shaft 22 projects outside of the carburetor where it is connected to a level 24. A spring means 26 has one end anchored to ange 116 and the other connected to lever 24 and urges throttle blade 14 into a closed position.

A control mechanism 28 comprises a housing 30 connected to an externally threaded barrel 32. Inside housing 30, a flexible diaphragm 34 divides the housing interior into two chambers 36 and 38. A rod 40 is connected to diaphragm 34 and extends through chamber 36 and barrel 32 to terminate a short distance outside of the end of barrel 32. Rod 40 serves as the movable stop means. An O-ring 42 seals the space between rod 40 and housing 30.

A positioning pad 44 is mounted concentrically with rod 40 within chamber 36, and a compressive spring 46 located by pad 44 bears on diaphragm 34. Barrel 32 is threaded into a bracket 48 fastened on carburetor body 10 by conventional means (not shown). A lock nut 50 is threaded on barrel 32 to prevent vibration from loosening the assembly. Chamber 36 is connected to the passage in the intake manifold by a short length of hose 52, and chamber 38 is connected to atmosphere by a bleed port 54.

FIGURE 1 operates in the following manner: When the engine is idling, the pressure in the intake manifold 20 is relatively low, with a typical value being a vacuum of about 16 inches of mercury. This vacuum is applied to chamber 36 via hose 52 where it overcomes the force of spring 46 and draws diaphragm 34 to the right, thereby moving rod 40 to the right. Rod 40 acts through lever 24 t0 hold throttle blade 14 open by a small amount sucient to idle the engine at about SOO-900 r.p.m.

When the ignition system of the engine is deactivated, the manifold pressure in intake manifold 20 rises to a vacuum of about 6-8 inches of mercury if the engine is dieseling, or to substantially atmospheric pressure if the engine has stopped all operation. Spring 46 overcomes the forces exerted on the diaphragm by manifold pressures greater than the vacuum produced by dieseling and moves diaphragm 34 to the left in FIGURE l. Rod 40 then permits lever 24 to pivot a short distance counterclockwise, thereby positioning throttle blade 14 where the air-fuel mixture flowing through induction passage 12 is substantially halted. Withoutfthis air-fuel mixture, the engine is unable to continue dieseling. n

Turning now to FIGURE 2, components which are the same as the components'in FIGURE l are designated by the saine numerals While the changed components are designated by primed tgersions 'of those numerals. On the carburetor itseif, a projecting tab 25 is added to the lower side of the lever 24. The housing 30 of control mechanismr'28 contains a diaphragmV 34' dividing the housing intontwo chambers 36 and 38 with chamber 36 being located at the rear of the housing. Chamber 36 is connected to the engineY intake VYmanifold by hose 52 and chamber 38 communicates with the atmosphere through port 54. i I

V:An aligning pad Y44 is fastened to the rear wall of housing 28', and a, compressive spring 46 is located by pad 44 and bears oh diaphragm 34. A rod 4Q is fastened to the other side of diaphragm 34 and passes through chamber Y38' and barrel 32'.Y At its outer end, rod 40,has a bent up tab 41' adaptedrto contact tab 25. Bracket 48 fastens the control valve to the carburetor flange by'any conventional fastening means. ,i i

The FIGURE 2 construction performs the same function asV the FIGURE l construction in a more etlicient manner. In FIGURE 2, when theV engine is idling and the manifold pressure is low, diaphragm 34 is drawn to the left and tab 2S contacts tab 41 in a slightly clockwise position of the throttle blade vwhere engine idling at a relatively high speed results. When the engine ignition system is turned olf, the manifold pressure rises toward atmospheric pressure and spring 46 urges diaphragm 34' and tab 41to the right so throttle blade 14has substantially closed by the time tab 25 stops against tab 41'.

The primary advantage of the FIGURE 2 construction liesl in the fact that the seal around rod 30 is eliminated. Without this seal, the friction forces acting on the rod are greatlyireduced and more accurate positioning can be accomplished.

During engine cranking, intake manifold pressure falls below a vacuum of 6" Hg and the force exerted on the diaphragm by this Vacuurn positions the stop means so Vthe throttle blade is opened to the engine idling position. In this positionthe throttle blade admits Yan additional fuel-air :mixture that assists in starting most engines. If, on the other hand, engine characteristics dictate starting with th mixture from the idlingY jets only, the control mechanism can be calibrated to hold the throttle blade in the closed position during cranking and move the blade to the idling position when the engine starts.

Thus, this invention provides a control means responsive to intake manifold pressure that permits higher engine idling speeds while positively preventing engine dieseling. The control means performs a stopping function only and does not interfere with normal operation of the throttle blade even though such operation might produce manifold pressures above and below the actuating point of the control Valve. In addition, the control means can be calibrated to assist inthe engine starting operation.

What is lclaimed is:

1. In an internal combustion engine having a metering device connected to an intake manifold, said metering device having a throttle blade for controlling flow and throttle closing means for urging said throttle blade toward its closed position, a control means for positioning said throttle blade according to the manifold pressure within said intake manifold comprising a movable stop means adapted to position said throttle blade in a partially open, engine idling position and a substantially closed engine 'stopping'V position when the throttle closing means moves the throttle blade toward itsclosed position and a pressure responsive means including a housing and a exiblediaphragm defining one wall of a chamber in said housing-said chamber communicating with i the intake manifold, said diaphragm being connected to said stop means, saidV pressure responsive means l moving' said stop means to said partially open, engine idling position when manifold pressure is relatively low and moving said stop means to said substantially closed engine stopping position when manifold pressure is relatively highY to prevent dieseling of said Y engine. i

2. Theengine of claim 1 in which the pressure responsive means movesY the stop' means to the engine stopping position whenever manifold pressure rises above a vacuum of about 8 inchesrof mercury. i

3. The engine of claim 2 in which the stop means comprises a member having a-tab means at its outer end, said tab means contacting a tab operably connected to the throttle blade to stop movement-of the throttle blade towards its closed position, said tabimeans permitting movementof the throttle blade to its substantially closed position when the intake manifold pressure is relatively high.

4.7lThe engine of claim 3 in which the control means positions the throttle-blade in an engine idlingzposition during engine cranking.

5. The engine of claim 4 in which the housing includes a pad means for bearing against said diaphragm to limit movement of said diaphragm in one direction whereby said pad means determines the position of the stop means providing the partially open,l engine idling position of the l throttle blade.

6. The engine of claim 5 Yin which the housing is threadably mounted to said metering device whereby rotating said housing relative to said metering device changes the position of the stop means when movement of the diaphragm limited Yby said pad.

7. The engine of claim 1 in which the housing includes a padmeans for bearingV against said diaphragm to limit movement of said diaphragm in one direction whereby said pad means determines the position of the stop means providing the partially open, engine idling position of the throttle blade.

8. The engine of claim 1 in which the housing is threadably mounted to said metering device whereby rotating said housing relative to said metering device changes the position of the stop means when movement of the diaphragm is limited by said pad.

References Cited UNITED STATES PATENTS 3,027,884 4/1962 Bale, et al. 12B-117.1 3,354,877 11/196-7 Zub et al.

1,262,013 4/1918 Callon.

1,461,662 7/1923 Kaw Amura.

1,960,432 5/1934 Barker et al.

WENDELL E. BURNS, Primary Examiner U.S. Cl. XR. 

